What this code means
P16E5 may mean the PCM is not receiving the expected DC-DC converter communication over the LIN circuit.
What the vehicle may do
- The vehicle may store the code with few noticeable symptoms.
- A warning message or charging-system-related complaint may be present.
- Electrical system behavior may be affected depending on the fault.
Possible fault areas
- Possible ignition feed or power-supply issue.
- Possible LIN circuit open, short, or connector issue.
- Possible fault involving a component connected to the LIN battery-sensor circuit.
- Possible DC-DC converter area concern.
- Possible PCM-side concern after the rest of the diagnostic path checks normal.
Diagnostic path
Opening context
On this Honda CR-V, P16E5 is a LIN communication error between the PCM and the DC-DC converter. In plain language, the PCM may not be receiving the DC-DC converter signal correctly over the LIN line. The vehicle may set a warning, may have charging or electrical system complaints, or may simply store the code with no obvious drivability symptom. Broadly, this can involve ignition feed, LIN wiring, connected LIN components, the DC-DC converter area, or, after the rest of the path checks normal, the PCM side. Start with the basic system checks, follow a structured diagnostic approach, and identify the parts in the test path before unplugging anything.
Choose the diagnostic path
Before getting deep into circuit testing, check whether the companion code is present. Do not read that as a failure by itself; use it to choose the inspection path. If that companion code is present, the path includes the shared IG1_ACG and LIN battery-sensor circuit checks, then the components connected to that LIN circuit. If it is not present, the path still starts with the shared IG1_ACG and LIN battery-sensor circuit checks, then moves into the DC-DC converter checks, DC-DC converter circuit checks, and finally the PCM conclusion if everything else tests normal.
Confirm the fault and prepare safely
Run the confirmation first: turn the vehicle to ON mode and wait 10 seconds. For any step where the PCM connector is going to be disconnected, jump the SCS line with the HDS and wait more than 1 minute before unplugging the PCM connector. That wait matters. Also, make sure the connector and terminal locations are positively identified before taking measurements; if they are not clear, pause and do not guess at meter lead placement.
Inspect the shared external circuit first
For the IG1_ACG and LIN battery-sensor circuit inspection, disconnect the DC-DC converter connector A, the PCM connector A, the alternator connector, the 12 volt battery sensor connector, and the shutter grille connector if the vehicle is equipped with a shutter grille. Then perform the circuit checks in order. With IG mode ON, the IG1_ACG circuit should show 12 V battery voltage. With IG mode OFF, the LIN open-wire check should be less than 1 Ω. For the LIN short-to-ground check, also with IG mode OFF, the normal result is more than 1 MΩ. Use the normal open-and-short inspection method and let the measured result drive the next move.
Evaluate the external circuit result
If that IG1_ACG or LIN battery-sensor circuit inspection is abnormal, treat it as a circuit problem and stay there until the circuit fault is located. If the abnormal result is in the power-supply portion of that inspection, continue with the additional power-supply inspection to narrow down where the failure is. Do not jump ahead to condemning a module while the external circuit is still abnormal.
If the companion-code path applies, isolate connected LIN components
When the path calls for checking the components connected to the LIN battery-sensor circuit, only do this after the external circuit is normal. Again, before disconnecting the PCM connector, jump the SCS line with the HDS and wait more than 1 minute. Disconnect the DC-DC converter connector A, PCM connector A, alternator connector, 12 volt battery sensor connector, and the shutter grille connector if equipped. Then reconnect the PCM connector, alternator connector, 12 volt battery sensor connector, and shutter grille connector one at a time while performing the inspection. The internal circuit condition should be not shorted. If the fault appears when one part is reconnected, the problem is with the part that shorted when it was brought back into the circuit. Some combined checks can be done early, but if a combined check fails, break the diagnosis back down and test each item individually.
If the no-companion-code path applies, check the DC-DC converter area
For the DC-DC converter inspection, understand the logic: there is no direct method here to test the DC-DC converter itself, so the diagnosis is done through the related components and circuits. Only continue after the external circuit is normal. Run the confirmation procedure and check the result for the companion code. If the result is normal, the problem points to the DC-DC converter. If the result is abnormal, the problem points back toward other related components.
Check the DC-DC converter circuit
Next, for the DC-DC converter circuit inspection, the same precautions apply: the external circuit must already be normal, and before disconnecting the PCM connector, jump the SCS line with the HDS and wait more than 1 minute. Disconnect PCM connector A, the alternator connector, the 12 volt battery sensor connector, and the shutter grille connector if equipped. Then perform the DC-DC converter circuit inspection. With IG mode OFF, the DC-DC converter internal circuit condition should be not shorted. If this inspection is abnormal, the problem is with the DC-DC converter. As with the other combined checks, if the broad test fails, slow down and isolate the failed item rather than guessing.
PCM conclusion and wrap-up
If the required inspection items all show normal, the remaining conclusion in this path is a PCM problem. For verification, keep it separate from the fault isolation: rerun the confirmation by turning the vehicle to ON mode and waiting 10 seconds, then confirm P16E5 stays gone. The takeaway is simple: diagnose P16E5 from the outside in — prove the shared power and LIN circuits first, isolate any LIN-connected part that shorts the line, then evaluate the DC-DC converter path before landing on the PCM. For more diagnostic training, visit stepdiagnostics.com.
Final check
Work the code from the shared external circuit toward the connected LIN components, DC-DC converter path, and only then the PCM conclusion.
For more guided automotive diagnostics, visit STEP Diagnostics.
